'People haven't been mentioning proportional partners' because it's bleedin' obvious and doesn't need explaining. Do you really think those of us who believe we get short changed by London think we should get 'equal' funding- 3 million people getting the same as 50 odd million? Per person in relation to the population. Jesus wept.
That's the simple part, but you have to consider socio-economic factors and reflect that in the funding to address the disparity between the wealthier areas of England and most areas of Wales. Sorry, this is probably over your head.